Universal Subscriber Identity Module (USIM) card or Subscriber Identity Module (SIM) card are used in Universal Mobile Telecommunications System (UMTS) third generation (3G) and Global System for Mobile communications (GSM) second generation (2G) terminals, respectively, for providing mobile phone service portability and security credential management. Global System for Mobile communications (GSM) is a widely deployed standard and is used world wide for mobile phone communications. The GSM technology is also known as a second generation (2G) technology. Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) standards for mobile phone communications.
Laptops and some portable computing devices presently have to have SIM or USIM cards embedded within the devices to obtain cellular services and thus tying the devices to a particular 2G or 3G cellular service provider at the time of manufacturing. This severely limits service portability across multiple devices because these embedded SIM or USIM cards are generally not user accessible.
In a different scenario, users may use a PC card with its own SIM or USIM slot to obtain cellular services and, thus, prevents factory-installed integrated wide-area wireless interface. In addition, most laptops currently have factory-installed Wi-Fi interfaces but users cannot use their SIM or USIM to pay for hotspot services without additional external readers and, thus, limiting Wi-Fi and cellular service bundling options. Wi-Fi is a wireless local area network (WLAN) technology based on the Institute of Electrical & Electronics Engineers (IEEE) 802.11 standards.